<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8"/>
    <meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1"/>
    <meta name="viewport"
          content="width=device-width, initial-scale=1, maximum-scale=1,minimum-scale=1, user-scalable=no">
    <title>bg</title>
    <link rel="shortcut icon" href="../img/logo.png" type="image/x-icon"/>
    <link rel="stylesheet" href="../css/bootstrap.css">
    <script src="../js/html5shiv.js"></script>
    <script src="../js/respondjs.js"></script>
    <script src="../js/jquery-3.4.1.js"></script>
    <script src="../js/bootstrap.js"></script>
</head>
<body>
<div class="container">
    <p class="text-center bg-danger">该段落使用了样式 "bg-danger"</p>
    <p class="text-center bg-info">该段落使用了样式 "bg-info"</p>
    <p class="text-center bg-success">该段落使用了样式 "bg-success"</p>
    <p class="text-center bg-primary">该段落使用了样式 "bg-primary"</p>
    <p class="text-center bg-warning">该段落使用了样式 "bg-warning"</p>
    <!-- 下拉箭头 -->
    <span class="caret"></span>
</div>
</body>
</html>
